The dependence of photocurrent and photovoltage of dye-sensitized solar cell on the incident light intensity were investigated based on the electron continuity diffusion equation. For the first time a model was presented for power loss of series resistance in dye-sensitized solar cell, and were simulated the influence of the active-area width of nanoporous film, the effect of special contact resistance on the photo-electric conversion efficiency, as well as the silver impedance in lager-scale solar cells with active area greater than 1 cm2 under different illuminations. It was found that the efficiency strongly depends on the width of active area and the silver impedance under strong illumination, nevertheless, this dependence is not obvious under poor illumination.